Nowadays, more and more sensors are applied in consumer electronic devices, such as mobile phones, tablet personal computers, and the like, for enhancing perceptions to various environmental parameters. For example, fingerprint sensors, ambient light sensors and proximity sensors are already widely used.
FIG. 1 schematically illustrates function of a conventional ambient light sensor. Normally, visible lights 101 in the outside surroundings may enter into the ambient light sensor, and be detected by a photosensitive device 102 (e.g. photosensitive diode) inside the ambient light sensor. The photosensitive device 102 can generate electric current which is proportional to the intensity of the received visible lights 101. Thereafter, the photon currents are detected and digitalized by a semiconductor chip (not shown in FIG. 1). The light currents generated by the photosensitive device 102 are proportional to the intensity of the received light, thus the light intensity can be represented by digital signals which are generated by the semiconductor chip based on the photon currents. As such, environment light 101 can be measured.
FIG. 2 schematically illustrates function of a conventional proximity sensor. Specifically, incident lights 202, generally infrared lights, are emitted from a light source 201 of the proximity sensor. Then the incident light 202 reach an object 203 and be reflected there, generating reflected lights 204. The reflected lights 204 are received by a detector 205, normally a photodiode, in the proximity sensor. As intensity of the reflected lights 204 received by the detector 205 is proportional to a distance between the detector 205 and the object 203, through detecting the light intensity of the reflected lights 204, the distance between the object 203 and the proximity sensor can be obtained.
Currently, there are generally two dominant fingerprint sensors, one is optical fingerprint sensor and the other is semiconductor capacitance fingerprint sensor. The optical fingerprint sensor generally includes focusing optical fingerprint sensor and non-focusing optical fingerprint sensor. The focusing fingerprint sensor implements fingerprint sensing by focusing fingerprint image light beams on the small-dimension optical sensor through light refractions and light reflections. However, the focusing optical fingerprint sensors generally have a larger thickness, which is one of the main drawbacks of the conventional focusing optical fingerprint sensors. Specifically, in order to focus light beams of fingerprint images, a finger with fingerprints should be put on an optical lens and irradiated by a built-in light source which is disposed on a bottom of the optical sensor. Lights emitted from the light source reach a triangular prism on which refractions of the lights occur and refracted lights will be generated. Then the refracted lights reach a surface of the finger on which reflections occur. Angles and intensity of reflected lights from ridge and valley of the fingerprint are different. As such, a spatial distribution image of the light intensity can be obtained. Thereafter, the image is focused on a charge-coupled device (e.g. CMOS pixel cell array or CCD pixel cell array) through devices such as triangular prisms, optical lens, and the like, so that a multi-gray fingerprint image can be obtained. Accordingly, triangular prisms and optical lens are required to implement the focus optical fingerprint sensor, thus the focus optical fingerprint sensor may has a long optical path and large in total thickness.
The non-focusing optical fingerprint sensor is implemented through ways as followed: lights emitted from a light source in the non-focusing optical fingerprint sensor reach a finger which is contacted with the sensor, generating reflected lights. The reflected lights then enter into the non-focusing optical fingerprint sensor for generating a fingerprint image according to light intensity and spatial distribution of the reflected lights. As light intensity and spatial distribution of the reflected lights may vary according to different shapes of the fingerprint, a valid fingerprint image can be obtained. Further, the fingerprint image obtained may have a size equal to that of the fingerprint.
Currently, fingerprint sensors, ambient light sensors and proximity sensors are generally integrated into electronic devices independently, which has following drawbacks.
From structure aspect, as multiple independent sensors can not share their components such as power sources, communication interfaces, light sources, and the like, with each other, multiple components are required to support these sensors. As such, devices with multiple independent sensors have complex structures, and cost is increased. Besides, as multiple independent sensors certainly take more interior spaces of electronic devices, the electronic devices may not be easily miniaturized and may be not portable as well when multiple independent sensors applied.
From manufacturing aspect, as multiple sensors are manufactured independently, the manufacturing process may have numerous complicated steps. Besides, these multiple sensors may be required to be packaged separately. As such, process difficulties may be increased and yield may be reduced. Furthermore, complicated manufacturing and packing processes can cause longer processing time, lower production efficiency and higher cost.
From application aspect, as multiple sensors are independent from each other, information collected by each sensor has no correlation and can not be shared. As such, each sensor has a single function and has no interaction with other sensors. Therefore, the multiple independent sensors may have lower application value.